Causes and risk factors

What causes cholangiocarcinoma (bile duct cancer)?The exact cause of cholangiocarcinoma is unclear. It is likely that this cancer arises due to a combination of factors, including other illnesses that cause chronic damage to the liver and/or bile ducts, certain toxins and possibly a small genetic predisposition, although it is not a directly inherited disease.

Although most cases of cholangiocarcinoma occur in people over 60 years of age, it appears to be increasing across all age groups including younger people. The cause of this ongoing rise is currently unknown.

The following risk factors are all accepted by scientists to increase the likelihood of developing cholangiocarcinoma:

• Primary sclerosing cholangitis (PSC)PSC, a condition where the bile ducts are chronically inflamed, is the commonest known predisposing cause of cholangiocarcinoma.

• Choledochal cystsCholedochal cysts are connected to the bile duct and fill with bile.Read More

• Bile duct stonesStones can develop in the common or hepatic bile ducts after infection or because of the slow movement of bile through the ducts. These stones can irritate the duct lining and cause inflammation, which can slightly increase the risk of cholangiocarcinoma.

• Liver flukeIn Southeast Asia, where cholangiocarcinoma is relatively common, associated risk factors include liver flukes and chronic typhoid, neither of which occurs in the Western world.

To read more about liver fluke and cholangiocarcinoma in Thailand, click here.

Other risk factorsOther recognised risk factors include gallstones which have remained stuck in the bile ducts for a long time; and exposure to certain toxins, such as Thorotrast, which was an X-ray contrast agent used several decades ago.

There is some evidence that long term liver damage of any cause, such as chronic viral hepatitis B or C, and alcohol may also be risk factors for cholangiocarcinoma. Newly discovered likely risk factors include obesity, diabetes and fatty liver disease. All these factors are suspected but not definitely proven to cause this disease.

The majority of people diagnosed in the West with cholangiocarcinoma have none of the risk factors mentioned above, their cholangiocarcinoma develops sporadically.

What causes gall bladder cancer?
Gallbladder cancer is more likely to occur in people who have a history of gallstones or in people who have inflammation of the gall bladder (cholecystitis). However, most people who have gallstones or an inflamed gall bladder won’t develop gall bladder cancer.

To read Tyson and El-Serag’s “Risk Factors for Cholangiocarcinoma” paper, which was published in the journal Hepatology, and in which they review scientific literature up to and including March 2011, click here